Hello Tom,
Do you mean article in documentation?
This provider allows you to map physical folders to for example rackspace. All this with help of custom file system provider . While this code:
// Creates a new StorageProvider instance using the custom 'CustomFileSystemProvider' assembly
var customMediaProvider = new StorageProvider("custom", "CustomFileSystemProvider");
// Maps a directory to the provider
StorageHelper.MapStoragePath("~/MySite/Media/", customMediaProvider);
Allows you to choose which provider will be used and which part of application path will be mapped to this provider. Provider code:
// Specifies the target root directory. The provider creates the relative path of the mapped folders within the given directory.
mediaProvider.CustomRootPath = @"D:\CustomMediaRoot";
// Maps a directory to the provider
StorageHelper.MapStoragePath("~/MySite/Media/", mediaProvider);
Maps its own path to shared drive and also maps part of application path to 3rd party. So by this, anytime a file in ~/MySite/Media/ folder will be requested, application will not use its own path, but it will try to locate files on @"D:\CustomMediaRoot". Similarly you can map files to rackspace. On rackspace part, you need to create Cloud files container which will provide you with unique URL, that you will be using to upload and serve files.